Mammalian ovulation is a complex process involving rupture of a mature follicle and extrusion of the oocyte. Theories which have been proposed to account for ovulation are: 1. increased follicular pressure results in ovulation, 2. inflammation weakens the follicle wall leading to rupture, 3. hydrolytic enzymes digest connective tissue in the follicle wall thereby promoting rupture, 4. smooth muscle and/or microfilament bearing cells contract to cause expulsion of the oocyte. The objective of the proposed research is to investigate the role of hydrolytic enzymes and contractile cells in the ovulatory process of mammals. We have developed a technique for experimentally examining the mechanism of ovulation in vivo. To do this, we have taken advantage of the fact that the hamster ovary is surrounded by a sac or bursa which is continuous with the oviduct. Topical application of chemical agents directly to the ovary can be made by injecting small volumes of fluid into the bursal space. The effect of agents on ovulation can then be directly assessed while the ovary is under natural regulation. This technique has numerous advantages over in vitro methods or injection of agents directly into the follicle. Various agents known to affect smooth muscle contraction (prostaglandins, catecholamines) and microfilament function (cytochalasin B) and to inhibit hydrolytic enzymes present in follicle walls will be tested using this in vivo technique, and their effects on ovulation established. Information obtained in this study will clarify the role of hydrolytic enzymes and contractile cells in the mechanism of ovulation.